Ok Jerry - I thought this thread was Hans expressing his viewpoint and various tradeoffs made as the kit designer. Obviously, those who are doing user-level modifications have greater freedom in terms of cost and other technical constraints as long as we can take the risks. Regarding freq response, class C/D/E/F have more stringent requirements in dynamic characteristics than class AB and it can be tough on high bands. But I don't think anyone is promoting BS170 as a universally good choice for final transistors, either.
Ryuji Suzuki AB1WX